In my opinion Lost Magic isn't really an RPG but more of a realtime strategy game.
You could try Lost in Blue. It's not really an RPG, either, more of an adventure... Well, try it anyway because it's awesome.
The only DS RPGs I remember playing are Contact which will probably be awesome when it's released in English and Deep Labyrinth which isn't really that great though the English version might help.
If you need to play an awesome RPG on your DS I suggest putting an English version of Mother for NES (also known as Earthbound Zero) on your Flashcart. There is also a translation patch for the first half of the Japanese Mother 1&2 Rom. That's what I am playing at the moment.
Edit: I don't know how far your basic Japanese will get you in these games but if you have a Flashcart you could just try it.

I was in a similar situation to you issac17 but I let myself slip on learning when my laptop got stolen. If you do not mind looking up the odd character every 5/10 minutes or so many Japanese RPGs are quite enjoyable and if you keep at it you will find that you know many Kanji well enough after a few weeks/months to play almost freely.

Cool, I guess first thing tomorrow I'm going to go pick up a DS Lite at bestbuy, along with the free 'brain age' game, and the 4GB media kit thingy. I'll try some japanese games, maybe it'll inspire me to get my japanese books back out.

Lost Magic is probably the best type of RTS you can make on the DS. It's also executed well from what I've played. However, it seems to include a lot of trial and error and the story is pretty lame. It's understandable that you are disappointed if you expected an RPG because Lost Magic isn't really an RPG.